5.3 swap with 700r4 --No Speedo or fuel gauge work HELP!
06-05-2013, 03:31 PM
#1
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5.3 swap with 700r4 --No Speedo or fuel gauge work HELP! Just like the title states I have a 5.3 swapped into my 90 obs silverado with the stock 700r4 and stock guages.
We've gone up and down this entire truck trying to find a reason why they aren't working. We used a PSI Conversions stand alone harness and just disc connected the old engine harness from where it wasn't needed. So NO wired have been cut at all.
We are just about burnt on this truck for this and this only reason. It besides a temp sensor and vss sensor code has ran great but this no speedo nor fuel gauge is just killing me. Due to the vss sensor and temp sensor codes its gotten really really poor mpg....km just hoping all this gets resolved. Someone must know what is going on!!
Just a FYI, 3 fill ups 2 20gallon and one 14gallon fill up in 9 days. My daily commute is 13 miles one way and I only had one day that was about 60 miles total. So no way it should be this bad.
Someone please help!!
We've gone up and down this entire truck trying to find a reason why they aren't working. We used a PSI Conversions stand alone harness and just disc connected the old engine harness from where it wasn't needed. So NO wired have been cut at all.
We are just about burnt on this truck for this and this only reason. It besides a temp sensor and vss sensor code has ran great but this no speedo nor fuel gauge is just killing me. Due to the vss sensor and temp sensor codes its gotten really really poor mpg....km just hoping all this gets resolved. Someone must know what is going on!!
Just a FYI, 3 fill ups 2 20gallon and one 14gallon fill up in 9 days. My daily commute is 13 miles one way and I only had one day that was about 60 miles total. So no way it should be this bad.
Someone please help!!
06-05-2013, 10:18 PM
#2
I can't believe you're only getting 5.4 mpg. If the fuel gauge doesn't work, how do you know how much fuel you've used? Maybe you're just adding fuel to the tank more than you're using??? The PSI harness should have a VSS plug, is it plugged in? You would need to hook your speedometer to the wire speed signal coming out of the PCM. The gas gauge is probably just no longer connected since you disconnected the old engine harness. You will have to trace the fuel gauge wire and wire it back into the cluster.
06-05-2013, 10:49 PM
#3
What was your fuel economy with the 33's BEFORE the swap? A friend put 33 or 35's on a truck and got horrible economy until he changed the gears. Something to think about if you changed tires at the same time the engine swap was done.
As previously mentioned, without starting with a full tank and knowing exactly how much you have burned you really can't comment about fuel economy. I helped a buddy do a swap in a 62 Impala and just like you he thought it was getting terrible economy. He also never completely filled the tank and his fuel sender was damaged thus he had no idea how much fuel he actually had. After fixing the sending unit issue he realized he was doing pretty good for a 60's car with 3.73 gears and a heavy right foot.
By the way, if you have a temp sensor code the engine WILL run like crap. That could also kill economy. An open short on temp sender will read something like -32 degrees which makes the PCM think the coolant is cold and the fueling and idle speed get bumped way up to compensate. You are essentially running massively rich all the time. I have HP Tuners so I can see all the sensors but any scanner that does live data will work.
As previously mentioned, without starting with a full tank and knowing exactly how much you have burned you really can't comment about fuel economy. I helped a buddy do a swap in a 62 Impala and just like you he thought it was getting terrible economy. He also never completely filled the tank and his fuel sender was damaged thus he had no idea how much fuel he actually had. After fixing the sending unit issue he realized he was doing pretty good for a 60's car with 3.73 gears and a heavy right foot.
By the way, if you have a temp sensor code the engine WILL run like crap. That could also kill economy. An open short on temp sender will read something like -32 degrees which makes the PCM think the coolant is cold and the fueling and idle speed get bumped way up to compensate. You are essentially running massively rich all the time. I have HP Tuners so I can see all the sensors but any scanner that does live data will work.
Last edited by gofastwclass; 06-05-2013 at 10:55 PM.
06-06-2013, 07:54 AM
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the way that I've been calculating miles per gallon is knowing how far my Drive is on a daily commute like to work is 13 miles one way. the numbers aren't exact but I have a roundabout number which came out to be a little over a hundred thirty miles on one fill up.the gas tank when empty fills up to 22 gallons no way I'm getting a hundred 30 ish even a hundred 150 on a 22 gallon tank.
33 inch tall tires before this whole motor swap. With the old 350 I was consistently getting 15 miles to the gallon during the summer and 13 in the winter. I also use my navigation on my smartphone to go from one gas station to the other just to find out what it really is burning. Straight highway cruising he got 13 miles to the gallon. 12 miles .92o gallons burned
33 inch tall tires before this whole motor swap. With the old 350 I was consistently getting 15 miles to the gallon during the summer and 13 in the winter. I also use my navigation on my smartphone to go from one gas station to the other just to find out what it really is burning. Straight highway cruising he got 13 miles to the gallon. 12 miles .92o gallons burned
06-06-2013, 01:51 PM
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He said it has nothing to do with his harness. I'm just baffled at the fact all guages besides volt and oil pressure stop working when no wires were cut and all necessary sensors and wires are still attached.
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06-06-2013, 06:20 PM
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Original transmission and the speedo is not working? Check grounds,fuses, plug...PSI is right, that should be working, regardless of whose harness.
If you are sending the VSS signal from the 90 model, did you program that info in when you had the computer flashed?
Guages not working- are you sure that your sensors are compatible with your dash guages.
I would definately run an extra ground or two to the motor as I have heard that insufficient ground can cause crazy problems......
If you are sending the VSS signal from the 90 model, did you program that info in when you had the computer flashed?
Guages not working- are you sure that your sensors are compatible with your dash guages.
I would definately run an extra ground or two to the motor as I have heard that insufficient ground can cause crazy problems......
06-06-2013, 10:13 PM
#10
How are you getting the single VSS sensor output from the 700r4 to both the original speedo and the PCM?
OBS truck fuel gauge is independent of the engine. Has to be something between the cluster and sender.
What's controlling the converter clutch?
OBS truck fuel gauge is independent of the engine. Has to be something between the cluster and sender.
What's controlling the converter clutch?
